Electric heater.



PATENTED MAR. 12, 1907.

J. T. HOWELL. ELECTRIC HEATER. APPLICATION FILED MAY 7. 1906.

// 571-1 we 11 to t 5 flll'unu s JAMES T. HOWELL, OF

PATENT OFFICE.

SEATTLE, WASHINGTON.

ELECTRIC HEATER.

Specification of Letters Patent.

Patented. March 12,1907. 7

Application filed May 7, 1906'. $erial Nc. 315,511.-

.To all whom it may concern:

Be it known that I, JAM'ES T. HOWEL a citizen of the United States, residing at Seattle, in the county of King and State of Washington, have invented certain new and useful Improvements in Electric Heaters, of which the following is a full,.clear, and exact description. I

My invention relates to electric heaters ofthat class employed particularly for heating water and other liquids by the aid of current from an ordinary lamp-circuit or other source of fixed potential.

The principal object of the invention is to provide a heater of this class having a resistance element of very large radiating or conducting area, so that the heat therefrom is I uickly and efficiently transmitted to the iiuidor material to he warmed and also so as to avoid the resistance material'or mediumitself becoming unduly heated, and thereby injured or destroyed.

A further object of the invention is to so construct the resistance element that perfect insulation is secured and all liability to grounds and short circuits overcome. A still further object of the invention is to protect the resistance material or wire from contact with the air, moisture, or other oxidizing influences.

With these and other objects in view my invention consists in the construction, combination, location, and arrangement of parts 'and in the order and sequence of ste s and operations, as hereinafter set fort and shown and finally particularly pointed out in the appended claims.

In the drawings, Figure l is a side view of a complete heater embodying the principles of my invention. Fig.2 is a detail sectional view illustrating the firststep of-the formation of the resistance element. Fig. 3"shows a following step in the construction of the resistance element, Fig. 4 indicates a slightlymodified construction, and Fig. 5 isa sectional view showing theinvention applied to heating a continuous current of Water flowing through a pipe.

The passage of an electric current through any poor conductor generates heat proportional to the potentialused; but the utilization of this principle for practicalheating purposes presents many difficulties. first lace the resistance material must have a fair y constant value in its resistance qualities, since otherwise an unequal current would In theilow at di'li'erent times. The form of resistance which best suits this condition is a section of comparatively fine metal wire of resisting qualities. The next important feature to be secured is a very large surface area through which the heat is transmitted. This is essential not only for the purpose of securing prompt and ellicient action, but also to preclude the resistance material itself becoming unduly heated at any point, as would be the case ifthe heat generated were not promptly carried away. In addition to this it is-important to have the msulationperfect at all points, since a ground or short circuit immediately results in destruction of the heater.

In carrying out my invention I aim to secure all the above desiderata and in a cheap and durable-form of construction.

Referringto the drawings, I have shown a heater having a handle 1 and a head 2 formed of a spirally coiled resistance element 3. The particular form of the resistance element 3 is unimportant and also its manner of support. It is evident that the resistance element would be difierently supported when used for warming a room than when employed for heating liquids. The disposition would also be varied in case the resistance element were applied to the purposes of cookiron. In the drawing 1 have shown the resistance element supported from the handle 1 by connecting-tube 4:, from which extend diverging arms 5, supporting the cross-arm structure 6. The ends of the resistance element extend up through the hollowconnec tion 4 to the terminal wires 3. The extremities -7 of'the cross-arms 6 are notched, as shown at 8, so as to receive the convolutions "of the resistance element. 9 indicates a similar cross-arm structure having notched extremities -10 opposed to the parts 7, above described. 11 designates an ordinary bolt connecting the cross-arm structures and by means 'of which the resistance element is securely held in" place therebetween. This particularconstruction gives a firm manner of supporting the resistance element and at the same time permits a ready flow of the liquid to be heated over the entire surface thereof. v j V.

Referring now more particularly to Figs. 2, 3, and 4, I have illustrated the preferred manner of constructing the resistance element. For'this purpose I' obtain a wire of resisting substance, preferably ironor Gering, or heating solid objects, such as a liatman silver, of suitable gagesay No. 2 3 l closing glass tube. Inasmuch as the glass and thread this wire or filament through a l small glass tube of the sort ordinarily procurable upon the market. 12 indicates the wire, and 13 the tube, at this stage of the manufacture. I now pass the glass tube through a metallic sheathing, preferably of copper, which can be obtained in straight lengths of suitable diameter. It is now merely necessary to expose the whole to heat in a furnace, so as to soften the copper sheathing and at the same time the glass tube within. When this is accomplished, the combined tubes can be readily bent into any desired form, as shown in Fig. 3, in which the copper part is shown at 14. This bending operation is accomplished without-difficulty,since the glass supports the metallic tubing and prevents its collapse during the bending operation. On the other hand, the metallic tubing has the effect of maintaining the temperature of the glass and keeping it equally softened throughout its length while the bending takes place.

tube is continuous from end to end, it is merely necessary to connect a pair of small platinum wires to the end of the resistance wire or medium and fuse the platinum into the glass. The ordinary terminals 3 may then be connected to the platinum ends. By this construction all possibility of any moisture entering the glass tube is precluded.

What I claim is 1. The method of forming a resistance ele ment which consists in threading a resist ance medium through a glass tube, placing the lass tube within a metallic sheathing, and bending the whole into desired form under the influence of heat.

2. The method of forming a resistance element, which consists in threading wire throu h a glass tube, inclosing the tube in a metal ic sheathing, and bending the whole under the influence of heat.

3. The method of forming a resistance ele- 3 ment, which consists in threading a resistln theabove way the resistance element is coiled orwound into any'desired shape. This may be a double spiral, as shown in Fig. 1, or a helical coil, as illustrated in Fig. 4, or any other shape.

ance-wire through an insulating medium, in-

closing the same within a hollow sheathing,

and bending the whole to any desired form.

4. A heatercomprising a resistance-wire, a

jvitreous tube surrounding said wire and In Fig. 4 a different form of insulating-wire is .used. described I sometimes make use of glass or porcelain beads 15, strung along the resisttamed in said outer tube whereby it is not ance-wire 12 at" uniformly-spaced intervals.

The metallic sheathing 14 is. separated from l the wire by the beads in the same way as by the glass tubeabove described, It is obvious that the beads prevent collapse of the casing when the element is bent exactly as in the previous case.

in some cases I use the invention for heat ing water which flows continuously through i My form or resistance element is par- 1 pipes.

In place of the glass tube 13 above ticularly suitable for this purpose,-since the j complete element may be threaded through Q an ordinary pipe 16, Fig. 5, and the fluid l passed through said pipe between its interior i wall and the exterior surface of the resistance element. In all cases the important desiderata of an electric heater are secured namely, the use of a resistance medium of sufficient fineness and length to utilize the ordinary potential drop of a lamp-circuit and at the same time present a'uniform electrical resistancethereto, and also the feature of a 5 large radiating or heat-conducting-area to secure quick and eflicient heating of the liq- 1 uids or articles desired and also to prevent undue rise of temperature in the resistance i 1 l l 1 adapted to seal the same against air and moisture, said tube being inclosed in an outer tube or sheathing ol heat-conducting material, the vitreous tube being loosely conbroken by slight bends or strains in the outer tube.

5. A resistance element, comprising a resistance-wire, a metallic tube or' sheathing, and an intermediate glass tube.

6. A resistance element, comprising a resistance-wire, a metallic tube or sheathing, and an intermediate glass tube, all bent to any desired form.

7. A heater comprising a resistance element, coiled into a spiral form, a pair of cross-arms for supporting said resistance element, means for connecting said cross-arms, and a-handle connected to one of said crossarms.

8. A heater, comprising a resistance element in the form of a double spiral coil, a pair of cross-arms engaging the respective coils, means for holding said cross-arms in clamping relation upon the coils,- and a han. dle connected to one of-said cross-arms, the ends of said resistance element being carried by and through said handle.

In witness whereof I subscribe my signa ture in the presence of two witnesses.

-' JAlilES 'l. HOWELL.

' \Vitnesses PHILIP H. FIELDING, FRANK S. Oman. 

